Source : Webster's Revised Unabridged Dictionary (1913)

Passing \Pass"ing\, a.
   1. Relating to the act of passing or going; going by, beyond,
      through, or away; departing.

   2. Exceeding; surpassing, eminent. --Chaucer. ``Her passing
      deformity.'' --Shak.

   {Passing note} (Mus.), a character including a passing tone.
      

   {Passing tone} (Mus.), a tone introduced between two other
      tones, on an unaccented portion of a measure, for the sake
      of smoother melody, but forming no essential part of the
      harmony.

Source : WordNet®

passing note
     n : a nonharmonic note inserted for transition between harmonic
         notes [syn: {passing tone}]